Four University of Michigan graduate students won Honorable Mentions at the 2018 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting. This is the flagship conference for those researching antenna, propagation, and radio sciences, with over 2,000 authors presenting their work.
The Michigan students who won Honorable Mentions are:
Title: “A Compact, Broadband, Two-Port Slot Antenna System for Full-Duplex Applications.”
Advisor: Professor Kamal Sarabandi
Spectrum crunch is one of the big challenges of the future ultra-dense wireless networks such as 5G and the Internet of Things. Very spectrally efficient wireless networks are to be developed to meet the requirements of these emerging technologies. The spectral efficiency of the wireless communication systems is predominantly limited by co-channel interference. Current prevalent transceivers contain transmitter and receiver pairs which operate in half-duplex mode to circumvent self-interference at the expense of cutting the throughput in half. Enabling a transceiver to operate in full-duplex mode gives rise to a twofold increase in the channel capacity. Full-duplex operation requires a daunting amount of self-interference cancellation, which is very challenging to achieve. This research work partly deals with the development of a compact antenna system with very high level of self-interference cancellation over a very wide bandwidth yet maintaining consistent radiation characteristics over the entire band. Used at Base Stations in cellular networks, this antenna can potentially provide services for twice as many users as that of the current cellular networks. Envisioned as the key element of the full-duplex radio repeaters to be adapted into 5G networks, the developed antenna system offers a significant increase in the available throughput to the end-users compared to the existing half-duplex repeaters. This antenna system also enables monostatic FMCW radars which are less expensive and require much less power compared to monostatic pulsed radars and have a wide range of applications such as autonomous vehicles, remote sensing, and biomedical imaging to name a few.
Title: “Full Wave Solutions of Multiple Scattering Using Vector Spheroidal Waves and Addition Theorem.”
Advisor: Professor Leung Tsang
We develop a hybrid method to calculate the multiple scattering of arbitrary-shape objects, based on the rigorous solutions of Maxwell equations in the form of Foldy-Lax multiple scattering equations (FL). The hybrid method includes three steps: (1) calculating the T matrix of each single object using vector spheroidal waves, (2) vector spheroidal wave transformations, and (3) solving FL for all the objects. We utilize the commercial software HFSS to calculate the T matrix of a single object. From the numerical integration of the scattered fields from HFSS with the vector spheroidal waves, the T matrix is obtained. To perform wave transformations (i.e. addition theorem) for vector spheroidal waves, we develop robust numerical methods. In solving FL, the coherent wave interactions among the objects are considered and the multiple scattering of all the objects is calculated. The hybrid method is applicable for full wave simulations of objects with arbitrary shapes, such as trees with arbitrary-shape branches and leaves.
Title: “Paired Metasurfaces for Amplitude and Phase Control of Wavefronts.”
Advisor: Professor Anthony Grbic
Lossless, passive, and reflectionless metasurfaces (two-dimensional arrays of subwavelength elements) can perform tailored manipulations of electromagnetic waves by modulating the phase profile of the wave. However, due to conservation of power flow, such metasurfaces cannot alter the amplitude of the wave as it is transmitted through the metasurface. In this paper, we show that two suchsequentially placed metasurfaces can be used to form desired amplitude and phase profiles of the wave without requiring losses, reflections, or gain. This approach allows custom aperture field profiles to be formed, in amplitude and phase, from arbitrary sources and makes the approach relevant to forming custom (shaped and steered) radiation patterns and three-dimensional holograms.
Title: "3D Electromagnetic Scattering from Multi-Layer Dielectric media with 2D Random Rough Interfaces Using T-Matrix Approach.”
Advisor: Leung Tsang
The Translation Matrix (T-Matrix) solution to the 3D problem of scattering of the electromagnetic waves from a dielectric layered medium with random rough interfaces is presented. The solution is based on the coupled vector integral equation of the electric field using the dyadic periodic Green’s function as a kernel. It is shown that the T-Matrix solution conserves energy, the bistatic scattering pattern is regular even in cases where guided modes within the layered medium are excited, and also that the method’s results coincide with those of the 2nd order Small Perturbation Method (SPM2) in the small height limit. One of the advantages of the T-matrix method compared to the SPM2 is the wide validity range of the solution which is also studied.
Posted July 20, 2018